Supercharging system



March 1955 H. u. LIEBERHERR 2,703,580

' SUPERCHARGING SYSTEM Filed Jan. 13, 1954 Invewzor jfans Zffz'ez5ererr(5y Par/fer Caraer United States Patent Oflice Patented Mar. 8, 1955SUPERCHARGIN G SYSTEM Hans U. Lieberherr, Paris, France, assignor toNordberg Manufacturing Company, Milwaukee, Wis., a corporation ofWisconsin /Application January 13, 1954, Serial No. 403,731

7 Claims. (Cl. 123-119) My invention resides in the field of internalcombustion engines and is an apparatus and method for substantiallyreducing the inlet temperature to the engine manifold while, at the sametime, increasing the inlet pressure of the air and its density tosubstantially increase the output of the engine.

A primary object of my invention is an engine with an improvedmechanical efliciency and an increased horsepower output.

Another object of my invention is an engine of the above type with amechanism for increasing its output without imposing a back pressure onthe engine exhaust.

Another object of my invention is an apparatus and method for increasingthe output of either combustion ignition, gas or spark ignition engines.

Another object of my invention is an apparatus and method of the abovetype constructed particularly for two-stroke cycle engines although itis not limited to them. Other objects of my invention will appear fromtime to time in the enusing specification and drawing which shows adiagrammatic illustration of the invention as applied to a conventionaltwo-stroke cycle engine.

In the drawing a conventional two-stroke cycle engine is indicatedgenerally at 10. A centrifugal compressor 12 draws in atmospheric airthrough an inlet 14. The air is compressed and discharged through anappropriate conduit 16 to a booster 18 which is connected to the driveshaft 20 of the engine through a suitable coupling 22. The boosteradditionally compresses the inlet air and discharges it through anappropriate conduit 24 to an intercooler 26. A cooling fluid enters theintercooler through an appropriate connection 28 and is dischargedthrough an outlet 30 after withdrawing the heat of compression from theair. The cool air from the intercooler is conveyed by an appropriateconduit 32 to an air turbine or veyed from the expander through anappropriate conduit 38 to the inlet manifold 40 of the engine. Theexhaust manifold 42 of the engine vents the exhaust gases to theatmosphere.

The use, operation and functions of my invention are as follows:

The compressor 12 draws in ambient atmospheric air and compresses it toan elevated temperature and pressure. This high pressure hot air isconveyed to the booster 18, which additionally elevates its temperatureand pressure by further compressing it. The hot high pressure air isthen conveyed to the intercooler where the heat of compression istransferred to the cooling fluid, but the pressure of the air ismaintained approximately constant. The cool high pressure air is thenconveyed to the expander 34 where, due to expansion, both its pressureand temperature are substantially reduced, but the pressure remainsabove atmospheric pressure. The cool air is then conveyed to the inletmanifold where it enters the cylinders and is compressed by the pistons.The pressure of the air entering the manifold is greater thanatmospheric and it will scavenge and supercharge the engine.

The booster 18 has only been represented diagrammatically. It should beunderstood that it is the volumetric type and could be either acentrifugal blower or a reciprocating piston pump. In any'case, thebooster 18 is coupled to the drive shaft in a suitable manner and itserves to meter the air passing through the unit as it compresses it.

My invention is particularly well suited to a two-stroke cycle engine,because a booster is normally present for scavenging purposes. Toincrease the output of a given two-stroke cycle engine by my invention,it is merely necessary to provide a compressor, such as 12, anintercooler such as 26, and an expander, such as 34, along with theappropriate connections.

To apply the invention to four-cycle engines would require, in additionto the other named elements, a booster such as 18, as it is not normallypresent.

When my invention is applied to a two-cycle engine, the booster 18serves a metering function and the quantity of air that is passedthrough it varies in accordance with the speed but not the load on theengine. On the other hand, as the load on a two-stroke cycle engineincreases, the pressure in the cylinders will increase and the periodfor scavenging air to flow through the cylinders will decrease. Thisdirectly affects the amount of expansion that takes place in theexpander 34, due to the increased pressure in the conduit 38. Therefore,the amount of expansion accomplished by the expander, and the cooling ofthe inlet air derived from it, will vary in direct relation to the load.

The expansion of the high pressure cool air in the expander 34 drivesthe shaft 36 and the compressor 12, and a part of the energy taken outof the high pressure air due to its expansion is used to drive thecompressor. The booster 18 provides sutficient excess energy ofcompression in the air so that the energy derived from expansion in theexpander 34 exceeds that required to drive the compressor 12. 4

It should be understood that the booster 18 is only a volumetric blowerof any conventional type, and the pressure increase in the air acquiredfrom the compressor and the booster exceeds the pressure drop in theexpander at all loads, so that a pressure differential exists betweenthe inlet and exhaust manifolds and the engine will be properlyscavenged and superchanged at all loads.

It will be realized that, whereas I have described and shown a practicaland operative device, nevertheless many changes may be made in the size,shape, and disposition of parts without departing from the spirit andscope of my invention. I therefore wish my description and drawings tobe taken as in a broad sense illustrative or diagrammatic rather than aslimiting me to my precise showing herein.

I claim:

1. In a device for cooling the inlet air for an internal combustionengine adapted to operate under varying load conditions, comprisingmeans for compressing the inlet air, an engine-driven booster to whichthe air is supplied from the compressing means for further compressingthe air, means for cooling the air from the booster, and means forexpanding the air from the cooling means and supplying it to the engine,the expanding means being associated with the compressing means to driveit.

2. In a device for cooling the inlet air for an internal combustionengine, comprising means for compressing the inlet air, a volumetriccompressor adapted to be driven by the engine to which the air issupplied from the compressing means for further compressing it, meansfor cooling the air from the volumetric compressor, and means forexpanding the air from the cooling means and adapted to supply it to theintake manifold of the engine, the expanding means being associated withthe compressing means to drive it.

3. In a device for cooling theinlet air for a two-stroke cycle internalcombustion engine having an engine-driven booster, comprising means forcompressing the inlet air and adapted to supply it to the engine-drivenbooster for further compressing it, means for cooling the air from thebooster, and means for expanding the air from the cooling means andadapted to supply it to the intake manifold of the engine, the expandingmeans being coupled to the compressing means to drive it.

4. A method of cooling the inlet air for an internal combustion engine,comprising the steps of initially compressing the inlet air, usingenergy from the engine for further compressing the air, cooling the airafter it has been further compressed, expanding the air after it hasbeen cooled, using the energy derived from expanding the air toinitially compress it, and supplying the coolair to the intake manifoldof the engine.

5. A method of cooling the inlet air for a two-stroke cycle internalcombustion engine having an engine-driven compressor comprising thesteps of initially compressing the inlet air, supplying the compressedair to the enginedriven compressor where it is further compressed,cooling the air after it has been further compressed by theengine-driven booster, expanding the air after it has been cooled, usingthe energy of expansion to initially compress the air, and supplying thecool air to the engine intake manifold.

6. A method of cooling the inlet air for an internal combustion engine,comprising the steps of initially compressing the inlet air to anelevated temperature and pressure, using energy from the engine forfurther compressing the air to a higher temperature and pressure,cooling the air to a reduced temperature while maintaining its pressureapproximately constant after it has been further compressed,

- expanding the air to a reduced temperature and pressure aboveatmospheric after it has been cooled, using the energy derived fromexpanding the air to initially compress it, and supplying the cool airto the intake manifold of the engine.

7. A method of cooling the inlet air for a two-stroke cycle internalcombustion engine having an engine-driven compressor comprising thesteps of initially compressing the inlet air to an elevated temperatureand pressure, supplying the compressed air to the engine-drivencompressor where it is further compressed to a higher temperature andpressure, cooling the air to a reduced temperature while maintaining itspressure approxmately constant after it has been further compressed bythe engine-driven booster, expanding the air to a reduced temperatureand pressure above atmospheric after it has been cooled, using theenergy of expansion to initially compress the air, and supplying thecool air to the engine intake manifold.

No references cited.

